Wall Effects on Combustion in an Engine.
Final rept. 15 Mar 83-14 May 84,
TRW SPACE AND TECHNOLOGY GROUP REDONDO BEACH CA ENGINEERING SCIENCES LAB
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This project utilized theoretical modeling and laboratory experiment to elucidate the role of chamber shaping on the combustion event in a four-stroke-cycle, reciprocating-piston-type internal-combustion-engine cylinder. First, theoretical modeling was carried out to evaluate heat transfer as a determent of end-gas knock during nonisobaric flame propagation across a homogeneous charge in a variable-volume enclosure. Via a semi-empirical model, turbulent combustion in an automotive cylinder was considered a three-zone generalization to encompass end gas, unburned bulk gas and burned gas of the standard two-zone Otto-cycle-combustion model was developed. Via a selfcontained model, laminar combustion in a specially designed rapid-compression machine was considered an asymptotic analysis valid in the limit of large Arrhenius activation temperature was developed. For given operating conditions, the fraction of the charge if any that undergoes autoconversion to product prior to flame arrival can be ascertained, along with the heat transfer sufficient to preclude such homogeneous explosion. Second, two-wall, or crevice-type, quenching of flame propagation through a stoichiometric or fuel-lean hydrocarbon-air-type premixture is examined because this phenomenon is now believed to be the major source of unburned-hydrocarbon emissions from homogeneous-charge engines.
- Combustion and Ignition
- Reciprocating and Rotating Engines